Scalable in Situ Synthesis of 2D-2D-Type Graphene-Wrapped SnS₂Nanohybrids for Enhanced Supercapacitor and Electrocatalytic Applications

Recently, the development of layered two-dimensional (2D) material-based nanostructured hybrids has witnessed a remarkable advancement as energy storage and conversion materials. Herein, we present an all-solid-state and scalable approach to integrate 2D-2D-type SnS2 and graphene-layered nanosheets (SnS2/G) and assessed its potential as an active material for the high-performance supercapacitor and electrocatalyst for the hydrogen evolution reaction (HER). In this in situ solvent-free strategy, a tin precursor and graphite oxide (GO) were homogeneously ball-milled with surfeit yet nontoxic elemental sulfur and subjected to a moderate thermal treatment to obtain a unique 2D-2D-type SnS2/G nanohybrid. The characterization revealed that the in situ formed SnS2 nanosheets were uniformly distributed and wrapped within graphene layers. The resulting nanohybrids demonstrated a superior specific capacitance of 565 F g-1 and retain a significant charge-discharge cyclic stability (90%/3000 cycles). Similarly, a resultant symmetric device delivered a high energy density of 23.5 Wh kg-1 and power density 880 W kg-1 at a current density of 1 A g-1. Furthermore, the resulting SnS2/G nanohybrid provided a much lower HER overpotential of 0.36 V than SnS2 (0.6 V) to attain a current density of 10 mA cm-2 in the alkaline electrolyte. The proposed strategy presents an environmentally benign avenue to integrate electrochemically active metal-sulfide-based 2D-2D-type nanostructured materials with superior energy storage and conversion capabilities.